1. Field of the Invention
The present invention relates to the field of printers that are responsive to electronic information signals for providing a hard copy print of electronically recorded information and, more particularly, to a printer for providing a color print of an electronically recorded image on an image-receiving sheet.
2. Description of the Prior Art
The present invention provides a compact and simply constructed printer for providing a hard copy color print of an electronically recorded image of a scene and is especially well suited for incorporation into a hand-held, self-processing, electronic imaging camera of the type disclosed in my commonly assigned copending application Ser. No. 891,705 filed on Mar. 30, 1978.
The printer embodying the present invention is of the scanning type in which an image receiving sheet is rotated on a drum while a print head mounting a plurality of printing transducers is advanced along the length of the drum to convert electronic image signals, representing different color components of a recorded image, into printing signals which are effective to cause the selective transfer of corresponding colored printing mediums from a transfer sheet to the image receiving sheet during a single scan thereby printing out a plurality of overlying dot-like patterns that define the image in much the same manner as a color half-tone lithographic printing process.
The printer also includes a mechanism that is actuable to automatically advance an image-receiving sheet from a cassette into operative relation with the drum and to advance or index an elongated transfer sheet to present a fresh set of colored printing medium stripes thereon for each successive print into operative alignment with the printing transducers. This feature substantially reduces the amount of manual manipulation of the printing materials required of the operator in making such a print.
Printers responsive to electronic image signals for making hard copy prints are known in the art but in general are not well suited for use in such a hand-held electronic imaging camera or other similar electronic image recording apparatus because of their large physical size, structural complexity or requiring multiple color application stations or multiple pass scans to provide a color print.
For example, the Sept. 5, 1977 issue of "Design News" at pages 36 and 37 describes a scanning type drum printer which prints out a color image of an electronically recorded image by selectively spraying droplets of red, yellow and blue ink onto an image-receiving sheet with image signal modulated jet spray nozzles. However, this device is quite large and complex and the need to store liquid inks and provide pressure pumps as well as the electronic modulating devices makes such an ink jet printer impractical for incorporation into a hand-held camera. Also, this printer does not include provisions for automatically advancing image-receiving sheets into operative relation with the drum.
U.S. Pat. No. 3,230,303 issued to A. Macovski et al on Jan. 18, 1966 is relevant for showing an electrostatic scanning type printer for making a multicolor print of an image in accordance with yellow, magenta, cyan and black image signals derived from photoelectrically scanning a multicolor original. The printer includes a drum 16 on which a dielectric paper 17 is supported for rotation while being scanned by an electrostatic stylus 34 that is modulated by one of the four image signals to form a first electrostatic image on paper 17. The first image is developed by dispensing a corresponding colored toner power from one of four boxes 70, 72, 74 and 76 and the first image is fixed at powder fixer station 78. The scanning, development and fixing process is then repeated in sequence for the remaining three image signals to form the color print. The extended time for making the print because of the multiple scans, the requirement for providing the toner powder boxes which must be replenished by the operator from time to time, and the lack of any mechanism for automatically advancing an image-receiving sheet into operative relation with the drum are characteristics that detract from the practicality of incorporating such a printer into a hand-held electronic image camera.
U.S. Pat. No. 3,780,214 issued to F. Bestenreiner et al on Dec. 18, 1973 is relevant for showing a printing apparatus for making a color print by the selective transfer of colored printing mediums from transfer sheets to an image-receiving sheet in accordance with electronic image signals. The printer comprises three printing stations A, B and C each of which included means for electronically modulating a laser beam in accordance with one of three color component image signals, means for advancing one of three colored transfer sheets past the modulated beam to melt or liquify a color pigment thereon to form a thermal image thereon and means for advancing an image-receiving sheet into contact with the transfer sheet to transfer the thermal image thereto. The image receiving sheet is fed from a long roll and is advanced sequentially to stations A, B and C such that the three colored images are applied thereto in overlying relation to form the color print. The complexity of the image receiving sheet transport mechanism required to assure that each of the thermal images are transferred thereto in proper registration and the space requirements for separate printing stations for each color preclude the use of this type of printer in a hand-held electronic imaging camera.